1. Field of the Invention
The present invention relates to an electronic device having an operation button manipulated by pressing it.
2. Description of Related Art
Recently, in car-mount acoustic devices, particularly among electronic devices, an operation button to be manipulated by pressing and having the same function as the operation button as provided in the device main body is placed on the steering wheel. It is intended to manipulate the operation button by remote control by connecting the operation button on the steering wheel and the device main body. The operation button provided on the steering wheel is usable simultaneously with the operation button of the device main body. Out of these operation buttons, the operation button pressed first is put in effect, and the operation according to manipulation of that operation button is carried out.
An example of operation button placed on the steering wheel to be manipulated by pressing is a volume UP/DOWN button for controlling the volume level of the power amplifier. As the volume UP/DOWN button is pressed by the user, operation signals showing the duration of the pressing operation and number of times of the pressing operation are supplied to the microcomputer. The microcomputer controls the power amplifier according to the operation signals to vary the gain thereof.
However, if dust particles are caught in the volume UP/DOWN button placed on the steering wheel or if the driver applies a larger force than required for pressing while turning the steering wheel, the pressed volume UP/DOWN button may be stuck in the pressed state without returning to the initial state. In such a case, if the power source of the device main body is turned on by the driver while the volume UP button is in pressed state, the operation signal from the volume UP button on the steering wheel is supplied to the microcomputer continuously from this moment. Thus, the volume level of the power amplifier increases, and the sound volume delivered from the speaker goes too much higher. As a result, the driver is exposed to an intolerable sound delivered from the speaker.
The present invention has been achieved in order to solve the above problems. It is an object of this invention to provide an electronic device configured not to operate according to an operation signal from an operation button in pressed state, if the operation button is in the pressed state when the power is supplied.
According to one aspect of the present invention, there is provided an electronic device including: an operation button to be manipulated by pressing; a judging unit for judging whether or not a voltage changed by pressing the operation button is equal to a specified value when an electric power is supplied; and a control unit for preventing a control corresponding to the signal from the operation button in pressed state from being executed when the judging unit judges that the voltage is not equal to the specified value.
In accordance with the electronic device thus configured, an operation button to be manipulated by a user is provided. When the electronic power is supplied to the electronic device, it is judged whether or not a voltage changed by pressing the operation button is equal to a specified value. If the voltage is equal to the specified value, the corresponding control is executed. On the contrary, if the voltage is not equal to the specified value, the corresponding control is not executed. For example, if the operation button is improperly being continuously pressed for some reason, the voltage does not take the specified value, and hence the corresponding control is prevented. The specified value may be a voltage showing the state that the operation button is not pressed.
According to another aspect of the present invention, there is provided an electronic device including: a first operation button provided in a device main body to be manipulated by pressing; a second operation button provided at a position remote from the device main body to be manipulated by pressing; a judging unit for judging whether a voltage changed by pressing of the first operation button and second operation button is equal to a first specified value or a second specified value when an electric power is supplied; and a control unit for preventing a control corresponding to the signal from the second operation button in pressed state from being executed when the judging unit judges that the voltage is not equal to the first specified value, and for preventing the control corresponding to the signal from the first operation button in pressed state from being executed when the judging unit judges that the voltage is not equal to the second specified value.
In accordance with the electronic device thus configured, a first operation button to be manipulated by a user is provided on the device main body, and a second operation button is provided remotely from the device main body. When the electronic power is supplied to the electronic device, it is judged whether or not a voltage changed by pressing the operation button is equal to one of a first specified value and a second specified value. If the voltage is not equal to the first specified value, the control corresponding to pressing the second operation button is not executed. If the voltage is not equal to the second specified value, the control corresponding to the first operation button is not executed. For example, if the operation button is improperly being continuously pressed for some reason, the voltage does not take the specified value, and hence the corresponding control is prevented. The specified value may be a voltage showing the state that the operation button is not pressed.
In an embodiment, the first specified value may be a voltage showing the state that the second operation button is not pressed, and the second specified value may be a voltage showing the state that the first operation button is not pressed.
The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiment of the invention when read in conjunction with the accompanying drawings briefly described below.